1. Field of the Invention
This invention relates to an image recording apparatus for recording images by rotating a recording drum with a recording medium mounted peripherally thereof.
2. Description of the Related Art
In such an image recording apparatus, the recording medium mounted peripherally of the recording drum is fixed to the peripheral surface of the recording drum by forward end clamps for fixing the forward end of the recording medium to the peripheral surface of the recording drum, and by rear end clamps for fixing the rear end of the recording medium to the peripheral surface of the recording drum.
On the other hand, in such an image recording apparatus, it is necessary to attach recording media of various sizes to the peripheral surface of the recording drum. For this purpose, the rear end clamps are constructed movable along recesses formed to extend circumferentially of the recording drum. Thus, the rear end clamps may be set to varied positions according to the lengths of recording media to be mounted peripherally of the recording drum.
In such an image recording apparatus, depending on the size of a recording medium mounted peripherally of the recording drum, an edge of the recording medium axially of the recording drum may be placed over one of the recesses extending circumferentially of the recording drum. In such a case, unless the rear end clamps apply an appropriate pressure to the recording medium, the edge of the recording medium will be lifted from the surface of the recording drum by a centrifugal force produced by rotation of the recording drum, or will yield to the pressure and sink in the recess. When such a phenomenon occurs, a laser beam emitted to the recording medium will go out of focus on the surface of the recording medium, thereby failing to record images properly.
To cope with the above situation, an image recording apparatus described in Japanese Patent No. 3595229 is constructed to adjust clamp rubber elements of rear end clamps to proper positions.
The rigidity of a recording medium to be mounted peripherally of the recording drum varies according to the type of the recording medium. Also, depending on the length of the recording medium lying over a recess formed to extend circumferentially of the recording drum, unless the rear end clamps apply to the recording medium an appropriate pressure according to that length, the edge of the recording medium will be lifted from the surface of the recording drum by a centrifugal force produced by rotation of the recording drum, or will yield to the pressure and sink in the recess. With the image recording apparatus described in the above patent No. 3,595,229, it is difficult to solve such a problem.